/*
 *                               POK header
 *
 * The following file is a part of the POK project. Any modification should
 * be made according to the POK licence. You CANNOT use this file or a part
 * of a file for your own project.
 *
 * For more information on the POK licence, please see our LICENCE FILE
 *
 * Please follow the coding guidelines described in doc/CODING_GUIDELINES
 *
 *                                      Copyright (c) 2007-2021 POK team
 */

/* @(#)s_frexp.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*
 * for non-zero x
 *	x = frexp(arg,&exp);
 * return a double fp quantity x such that 0.5 <= |x| <1.0
 * and the corresponding binary exponent "exp". That is
 *	arg = x*2^exp.
 * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
 * with *exp=0.
 */

#ifdef POK_NEEDS_LIBMATH

#include "math_private.h"
#include <libm.h>

static const double two54 =
    1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */

double frexp(double x, int *eptr) {
  int32_t hx, ix, lx;
  EXTRACT_WORDS(hx, lx, x);
  ix = 0x7fffffff & hx;
  *eptr = 0;
  if (ix >= 0x7ff00000 || ((ix | lx) == 0))
    return x;            /* 0,inf,nan */
  if (ix < 0x00100000) { /* subnormal */
    x *= two54;
    GET_HIGH_WORD(hx, x);
    ix = hx & 0x7fffffff;
    *eptr = -54;
  }
  *eptr += ((uint32_t)ix >> 20) - 1022;
  hx = (hx & 0x800fffff) | 0x3fe00000;
  SET_HIGH_WORD(x, hx);
  return x;
}

#endif
